Here's an example. is played to reduce White's framework;
is correct shape in reply. -- Charles Matthews.
In this situation Black answers the keima slide of with the kosumi of
. This is a common joseki. -- Bill Spight
Here's another well-known joseki example of a kosumi response to a keima approach.
This means to play kosumi (diagonal move) when your opponent plays a keima (knight's move) approach to your stone. Your kosumi will be on the point that the approach aimed at. It also aims at a shoulder hit (katatsuki) against your opponent's stone.
Take for example the following situation that often arises in a handicap game:
White approaches at (keima in relation to Black's corner stone). Next Black plays at
answering a keima with kosumi.
After
and
, White will stabilize the group with a play
around a. Note that the aim of
is not to secure
territory in the corner. White can still invade at b later on.
Instead it denies
access to the corner, thus keeping this
stone from easily securing a base: the white group remains weak.
-- Arno Hollosi
Bill Spight: Actually, is a kosumitsuke. I would have thought that answering keima with kosumi meant something like this (Shusaku kosumi):
Isn't there another joseki when white plays at '1', black responds at the position which white had played '3' and then white will play a hane and the joseki continues...? Random Passerby?
But this, while joseki, is slow, and is usually avoided. The kosumi-tsuke is good to know, but also relies on the surroundings. You would not typically respond with either kosumi or kosumi-tsuke to a keima kakari.
This seems to be a misconception these days, as the kosumi response to the keima kakari is seen often in pro play. -- Anon
So how come this is a "proverb"? Aside from here, I have seen it only on Jan van der Steen's list, and did not find an explanation there.
The other way around makes more sense:
is a keima response to the kosumi of
. That is joseki.
Bob McGuigan: First, all proverbs have exceptions and are only meant to suggest a proper way to play. The correct move in a situation always depends on the over-all board position. In the preceding diagram is a kosumi but doesn't have the same relationship to the corner 3-4 stone. Also,
is not the only joseki response to
, there are several "non-keima" possibilities.
See also keima slide and ogeima slide.